ABSTRACT In the U.S., approximately 40% of the population has some hyperglycemic condition. Worksite interventions offer a promising framework for delivering public health interventions to people with prediabetes, since worksites reach a large segment of the population for most of their adult life. The opportunity for long-term follow-up and support may be greater through worksites than through clinic-based programs. Worksite interventions that promote weight loss through lifestyle modification reduce risk for type 2 diabetes among those at high-risk. However, there is heterogeneity in the weight loss response following a standard lifestyle intervention, and early non-response to treatment is an indicator of treatment success. Stepped, or augmented, care can be effective in promoting additional weight loss among early non-responders. Furthermore, effective treatments for weight loss maintenance, especially at the worksite, are not well known. Ongoing contact and support, frequent self-weighing, and skill building in problem solving and barrier reduction offer promise as intervention strategies for weight loss maintenance. Therefore, the purpose of this study is to evaluate the impact of the standard 16-week, goal-based Group Lifestyle Balance (GLB) intervention for diabetes prevention to an alternate version of the intervention (GLB+) that is restructured with training in cognitive and emotional agency for change, problem solving, and goal attainment. University employees who are at least 21 years old with prediabetes (n=236) will be recruited and receive the first 4 weeks of the standard GLB intervention. Participants who fail to achieve 2.5% weight loss at intervention week 5 will receive the GLB+ intervention for the remaining 12 weeks. The 16-week core intervention phase then will be followed by an 8-month extended intervention phase to promote weight loss maintenance. Following the core intervention phase, matched pairs of participants will be created based on gender and percent weight change from baseline. Each person in the pair will be randomly assigned to either the extended intervention phase of the standard GLB intervention or to the extended intervention phase of the GLB+ intervention. A 6-month no contact maintenance phase will follow the extended intervention phase. The impact of the interventions on percent change in weight (primary outcome), fasting glucose, lipid panel, blood pressure, dietary intake, physical activity, quality of life, and constructs related to problem solving and goal setting will be determined at 4, 12, and 18 months. Cost effectiveness analysis also will be conducted to determine if the benefits associated with weight change justify the costs associated with intervention augmentation. The proposed study will enable evaluation of a practical approach for a sustainable diabetes prevention program at a university worksite and the impact of augmented care on early non-response to treatment and on weight loss maintenance.